1. Field of the Invention
The invention relates to a portable electronic device, more particularly, a portable electronic device with a multiple-frequency antenna.
2. Description of the Related Art
Planar inverted F antennas (PIFA) and loop antennas are two conventional designs of antennas. The resonant length of a PIFA is about one quarter of a wavelength. The resonant length of a loop antenna is about one half of the wavelength. Therefore, the area required to adapt a PIFA is smaller than that for a loop antenna. Since the trend in designing the exterior of most electronic devices nowadays (e.g. mobile phones, tablet computers) tend toward small and thin, it is not easy to fit loop antennas into these small and thin portable electronic devices. On top of that, some exterior designs use metallic materials, causing reductions in efficiency of the built-in PIFA. Loop antennas, on the other hand, are not as easily affected by metals or human body contact. Therefore, the invention looks into how to create a portable electronic device that fits into both exterior design and antenna design specifications.